This invention relates to a thermal head and, in particular, to a thermal printing/recording device such as a printer or a facsimile adopting the thermal head printing method, the thermal transfer printing method, or the thermal ink-jet printing method.
A thermal head has, on a ceramic substrate subjected to a glass-glazing treatment, a plurality of heating elements comprising heating resistors, and electrical conductors for supplying power to the heating elements. Corresponding heating elements are turned on and heated by means of the electrical conductors so as to obtain an appropriate heat pattern in accordance with the data to be recorded, thereby performing printing.
Ceramic substrates are usually obtained by polishing a flat ceramic plate to a given smoothness. A thermal head of this type is called a planar thermal head.
However, such a thermal head requires polishing of a high cost, resulting in an expensive thermal head. In addition, when a printing sheet is inserted or a film-like intermediate medium (such as a thermal head ink ribbon film) is inserted between the printing sheet and the head, a sufficient space is needed therearound, resulting in a large device.
Recently, therefore, an end-face type thermal head has often been used. This thermal head has a driver circuit for driving the heating elements mounted on a face different from that of the heating elements and also has a small head width and projection-like heating elements.
With the conventional end-face type thermal head, however, since the current supplied to a common electrode amounts to a maximum of several amperes, heat tends to be generated.
In addition, since the common electrode is arranged on a side opposite that on which the driver circuit is mounted and is connected to a power supply substrate, the manufacturing steps become complex, resulting in high cost.